This invention relates to a centrifugal pulp screen used in paper manufacturing and particularly to the construction of a cylindrical screen member of the centrifugal pulp screen.
In order to get homogeneous pulp in paper manufacturing, the impurities in the pulp must be removed, usually by sifting the pulp through a series of screening processes in various screening machines. Referring to FIG. 1, pulp flows through a pulp screening machine (1) in a direction indicated by the arrows. A rotor (2) is located at a center of the screening machine. The bottom end of the rotor extends through the bottom of the screening machine (1) and is attached to a band wheel (3) to be driven by a motor (not shown). Two support plates (4) (4') are provided in the screening machine to mount a cylindrical screen member (5) therebetween, so that the screen member (5) surrounds the rotor (2). The support plate (4) defines by partition two spaces which respectively receive the inflow and the efflux of the pulp. Referring to FIGS. 2 and 2A, there are a plurality of axially elongated parallel radial through-holes (6) in the cylindrical screen member (5). Each of the through-holes has an inlet (6') on the inside of the screen member and an outlet (6") on the outside of the screen member for the pulp particles to flow through. When the pulp is agitated and forced by the rotor to flow through the screen member, the through-holes are liable to be come clogged. The pulp disposal efficiency of the screen member is decreased and the efficiency of the motor is reduced, when this situation occurs.